Convenience of daily life is improved along with science and technology progress. However, environment noise from transportation and industry causes damages on the sense of hearing. Presently, methods for noise cancellation are classified into passive noise control (PNC) and active noise control (ANC). Passive noise control is sound reduction by noise-isolating material such as sound-absorbing cotton. However, passive noise control neither truly eliminates noise nor totally overcomes low-frequency noise even using thick and weighty sound-absorbing cotton. Therefore, passive noise control neither resolves environment noise issue nor is convenient to be portable. Active noise control is a method for reducing unwanted sound by the addition of anti-noise. The anti-noise, whose phase is opposite to noise but amplitude is same as the ones of noise, is generated by a speaker according to a result of environment noise detection by a microphone. The environment noise cancellation can be achieved with the anti-noise to destroy strength of noise by forming destructive interference.
Presently, a helmet with active noise control combines an active noise control system into the helmet, which may provide a rider's head protection and environment noise cancellation. However, high cost results in little utilization frequency for such the helmet, except in aircraft industry, people working at aircraft stations protect themselves with such the helmets against noises from engines of aircraft.
US patent application of publication No. 20050117754 discloses a helmet of active noise cancellation, a vehicle system thereof and a method therefor. A rider may use an adaptive active noise control to cancel noise from wind, other vehicles and environment for improvement of riding quality. However, this helmet does not have noise cancellation combined with music preservation function and the peripheral circuit cost therefor is still too expensive.
Accordingly, the present invention provides an electronic helmet, and especially, an electronic helmet and cancellation method to integrate active noise control, hands-free communication, music listening, and voice navigation for noise cancellation.